If you look closely, a halo of distortion surrounds the person walking out to the platform. This is because the subject walking out to the platform was superimposed over video of the passing train, probably by using a very soft oval dissolve or wipe.

When using this technique, you must be careful not to overlap the two moving subjects. This is why you see a jump cut when the train meets the subject and is also the reason why it's shot with the alleged collision happening at the far right of the frame.

This video was done by simply mounting a camera on a tripod and framing the shot to capture a passing train AND capture a person walking out to the edge of the platform who becomes somewhat stationary at the edge of the frame.
Simply roll tape as the train approaches and move to where you want the subject to enter the shot. As soon as the train passes, you walk into frame, out to the edge of the platform and stand there. This way the background details and lighting will be very close. Then using a very soft oval wipe, superimpose the subject walking to the platform edge over video of the passing train only up to the point of the supposed impact.

Having taken film production in college, I can tell that this was shot on a Sunday afternoon, at the last minute, was due sometime around 2pm on Monday and he didn't have anyone available to use as a subject but himself. Been there.